import java.util.HashMap;

public class num3 {
    public int lengthOfLongestSubstring(String s) {
        if(s.length() == 0) {
            return 0;
        }
        HashMap<Character,Integer> map = new HashMap<>();
        int left = 0;
        int max = 0;
        for (int i = 0; i < s.length(); i++) {
            if(map.containsKey(s.charAt(i))) {
                left = Math.max(left,map.get(s.charAt(i)) + 1);
            }
            map.put(s.charAt(i),i);
            max = Math.max(max,i - left + 1);
        }
        return max;
    }
}
